Newsweek columns of liberal economist Samuelson, 1968-81, to place alongside Newsweek columns of conservative economist Friedman (p. 350)--with the difference that, as Samuelson hints in his brief prefatory remarks, Friedman is more the polemicist. . . and Samuelson, responding to the passing breezes, is more often wrong. (Just how wrong? ""Since 1975 America has been in a vigorous recovery,"" he writes cheerily in 1979.) The book is intelligently and helpfully edited for the novice, however (Keating's section-introductions put the columns in temporal and theoretical perspective); it offers sidelights for the knowledgeable browser, and a clue-in to readers in the coming years. Economic advice and free-associating (""The cliches about Adam Smith turn out on reflection to be largely true"") commingles, indeed, with observations on the new Social Darwinism, sociobiology (a discipline because Descartes-like, ""I have a textbook written about me"") and on Mrs. Gandhi's throttling of Indian democracy (unprotested by American intellectuals). There is practical counsel: ""The main recipe for no-fuss canny investing: make great use of no-load mutual funds. . . . This leaves you free to fish, philander or perfect your mousetrap. What you lose is the daydream of one big killing. What you gain is sleep."" There are also, in the economic sphere, recurrent motifs. From an open letter, in 1979, to candidate Kennedy: ""The center way is the hard way. But for the 1980s, it's the only way."" And from the world at large comes admonitory good news: ""higher per capita income does indeed buy longer life and better health."" (The same is true, naturally, at home.) Deftly turned, lightly philosophical pieces, in tote--with some ponderings on such knotty problems as ""the decline of the bourgeoisie.